'\" t
.\"     Title: dblink_get_pkey
.\"    Author: The PostgreSQL Global Development Group
.\" Generator: DocBook XSL Stylesheets v1.79.1 <http://docbook.sf.net/>
.\"      Date: 2021
.\"    Manual: PostgreSQL 13.3 Documentation
.\"    Source: PostgreSQL 13.3
.\"  Language: English
.\"
.TH "DBLINK_GET_PKEY" "3" "2021" "PostgreSQL 13.3" "PostgreSQL 13.3 Documentation"
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.SH "NAME"
dblink_get_pkey \- returns the positions and field names of a relation\*(Aqs primary key fields
.SH "SYNOPSIS"
.sp
.nf
dblink_get_pkey(text relname) returns setof dblink_pkey_results
.fi
.SH "DESCRIPTION"
.PP
\fBdblink_get_pkey\fR
provides information about the primary key of a relation in the local database\&. This is sometimes useful in generating queries to be sent to remote databases\&.
.SH "ARGUMENTS"
.PP
\fIrelname\fR
.RS 4
Name of a local relation, for example
foo
or
myschema\&.mytab\&. Include double quotes if the name is mixed\-case or contains special characters, for example
"FooBar"; without quotes, the string will be folded to lower case\&.
.RE
.SH "RETURN VALUE"
.PP
Returns one row for each primary key field, or no rows if the relation has no primary key\&. The result row type is defined as
.sp
.if n \{\
.RS 4
.\}
.nf
CREATE TYPE dblink_pkey_results AS (position int, colname text);
.fi
.if n \{\
.RE
.\}
.sp
The
position
column simply runs from 1 to
\fIN\fR; it is the number of the field within the primary key, not the number within the table\*(Aqs columns\&.
.SH "EXAMPLES"
.sp
.if n \{\
.RS 4
.\}
.nf
CREATE TABLE foobar (
    f1 int,
    f2 int,
    f3 int,
    PRIMARY KEY (f1, f2, f3)
);
CREATE TABLE

SELECT * FROM dblink_get_pkey(\*(Aqfoobar\*(Aq);
 position | colname
\-\-\-\-\-\-\-\-\-\-+\-\-\-\-\-\-\-\-\-
        1 | f1
        2 | f2
        3 | f3
(3 rows)
.fi
.if n \{\
.RE
.\}
